Search results for "Atomic layer"
showing 10 items of 140 documents
Low-temperature atomic layer deposition of ZnO thin films: Control of crystallinity and orientation
2011
Abstract Low-temperature atomic layer deposition (ALD) processes are intensely looked for to extend the usability of the technique to applications where sensitive substrates such as polymers or biological materials need to be coated by high-quality thin films. A preferred film orientation, on the other hand, is often required to enhance the desired film properties. Here we demonstrate that smooth, crystalline ZnO thin films can be deposited from diethylzinc and water by ALD even at room temperature. The depositions were carried out on Si(100) substrates in the temperature range from 23 to 140 °C. Highly c-axis-oriented films were realized at temperatures below ~ 80 °C. The film crystallinit…
Hardness and modulus of elasticity of atomic layer deposited Al2O3-ZrO2 nanolaminates and mixtures
2020
This work was funded by the European Regional Development Fund project TK134 “Emerging orders in quantum and nanomaterials”, Estonian Research Agency project PRG4 “Emerging novel phases in strongly frustrated quantum magnets”.
Atomic layer deposition of Ti-Nb-O thin films onto electrospun fibers for fibrous and tubular catalyst support structures
2018
Here, the authors report on the preparation of core-shell carbon-ceramic fibrous as well as ceramic tubular catalyst supports utilizing electrospinning and atomic layer deposition (ALD). In this paper, ALD of Ti-Nb-O thin films using TiCl4, Nb(OEt)5, and H2O as precursors is demonstrated. According to the time-of-flight-elastic recoil detection analysis and Rutherford backscattering spectrometry, carbon and hydrogen impurities were relatively low, but depend on the pulsing ratio of the precursors. Optimized ALD process was used for coating of sacrificial electrospun polyvinyl alcohol (PVA) template fibers to yield tubular Ti-Nb-O structures after thermal or solution based PVA removal. Anoth…
Crystal Reorientation and Amorphization Induced by Stressing Efficient and Stable P–I–N Vacuum‐Processed MAPbI 3 Perovskite Solar Cells
2021
Herein, the long-term stability of vacuum-deposited methylammonium lead iodide (MAPbI(3)) perovskite solar cells (PSCs) with power conversion efficiencies (PCEs) of around 19% is evaluated. A low-temperature atomic layer deposition (ALD) Al2O3 coating is developed and used to protect the MAPbI(3) layers and the solar cells from environmental agents. The ALD encapsulation enables the MAPbI(3) to be exposed to temperatures as high as 150 degrees C for several hours without change in color. It also improves the thermal stability of the solar cells, which maintain 80% of the initial PCEs after aging for approximate to 40 and 37days at 65 and 85 degrees C, respectively. However, room-temperature…
Normal Metal-Insulator-Superconductor Tunnel Junctions With Pulsed Laser Deposited Titanium Nitride as Superconductor
2021
Here we report the fabrication of normal metal – insulator – superconductor (NIS) tunnel junctions using superconducting titanium nitride grown by pulsed laser deposition (PLD). The films for NIS junction fabrication were deposited on two different substrates: silicon nitride film and magnesium oxide. TiN films were characterized by means of electrical transport measurements, and films with superconducting transition temperatures above the liquid helium boiling point were chosen for fabrication of NIS junctions. Tunnel junction devices were successfully fabricated using electron beam lithography and shadow evaporation techniques. The insulator layer formation was performed using two differe…
The co-reactant role during plasma enhanced atomic layer deposition of palladium
2020
Atomic layer deposition (ALD) of noble metals is an attractive technology potentially applied in nanoelectronics and catalysis. Unlike the combustion-like mechanism shown by other noble metal ALD processes, the main palladium (Pd) ALD process using palladium(ii)hexafluoroacetylacetonate [Pd(hfac)2] as precursor is based on true reducing surface chemistry. In this work, a thorough investigation of plasma-enhanced Pd ALD is carried out by employing this precursor with different plasmas (H2*, NH3*, O2*) and plasma sequences (H2* + O2*, O2* + H2*) as co-reactants at varying temperatures, providing insights in the co-reactant and temperature dependence of the Pd growth per cycle (GPC). At all te…
Atomic Layer Deposition of Localized Boron- and Hydrogen-Doped Aluminum Oxide Using Trimethyl Borate as a Dopant Precursor
2020
Atomic layer deposition (ALD) of boron-containing films has been mainly studied for use in two-dimensional materials and for B doping of Si. Furthermore, lithium-containing borates show great promi...
Atomic layer deposition of ternary ruthenates by combining metalorganic precursors with RuO4 as the co-reactant
2022
In this work, the use of ruthenium tetroxide (RuO4) as a co-reactant for atomic layer deposition (ALD) is reported. The role of RuO4 as a co-reactant is twofold: it acts both as an oxidizing agent and as a Ru source. It is demonstrated that ALD of a ternary Ru-containing metal oxide (i.e. a metal ruthenate) can be achieved by combining a metalorganic precursor with RuO4 in a two-step process. RuO4 is proposed to combust the organic ligands of the adsorbed precursor molecules while also binding RuO2 to the surface. As a proof of concept two metal ruthenate processes are developed: one for aluminum ruthenate, by combining trimethylaluminum (TMA) with RuO4; and one for platinum ruthenate, by c…
Plasma-Enhanced Atomic Layer Deposition of Silver Thin Films
2011
Thermal properties of various silver precursors known in the literature were evaluated in order to discover which precursor is the most suitable one for plasma-enhanced atomic layer deposition (PEALD) of silver thin films. Ag(fod)(PEt3) (fod = 2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) was found to be the best choice. Using Ag(fod)(PEt3) together with plasma-activated hydrogen, silver thin films were deposited at growth temperatures of 120–150 °C, and ALD-type saturative growth was achieved at 120–140 °C. At 120 °C, the growth rate was 0.03 nm per cycle. The plasma exposure time had also an effect on the growth rate: with shorter exposure times, the growth rate was lower over…
Iridium metal and iridium oxide thin films grown by atomic layer deposition at low temperatures
2011
Atomic layer deposition (ALD) of both iridium and iridium oxide films at low temperatures has been studied and the resulting films have been examined by XRD, FESEM, XRR, EDX, AFM, TOF-ERDA, and four point probe measurements. Iridium oxide films were successfully grown using (MeCp)Ir(CHD) and ozone between 100 and 180 °C, however, the density of the films substantially reduced at 120 °C and below. The density reduction was accompanied by a phase change from crystalline to amorphous IrO2. Metallic iridium films were deposited between 120 and 180 °C by adding a reductive hydrogen pulse after the oxidative ozone pulse. Comparison of these processes with the earlier process employing the same Ir…